[unreadable] The University of Arizona proposes to acquire a ThermoFinnigan LTQ-FT high performance mass spectrometer (MS). This instrument will be placed in the UA Mass Spectrometry Facility and operated by staff of the MS facility and the proteomics facilities. This instrument's main attractive features are that it combines linear ion trap (LTQ) high throughput performance on an HPLC timescale with ion cyclotron resonance (FTMS) high resolution and high mass accuracy. FTMS resolution of 100,000-500,000 provides mass accuracy of 1-2 ppm, and the LTQ provides sensitivity in the sub-fmol range. Fragmentation by collision-induced dissociation and electron capture dissociation are possible and provide complementary fragmentation information. Infrared multiphoton dissociation can provide information similar to CID, but with the possibility of activating fragment ions as well as precursor ions and can be used to pre-heat ions for ECD. A major user group that already uses mass spectrometry to solve biological or medical problems, but who have faced limitations in their research because they do not have access to a higher performance instrument such as the LTQ-FT, has been identified. These include faculty from Biochemistry and Molecular Biophysics (Vierling, Little), Pharmacology and Toxicology (Lau, Monks, and Vaillancourt), the Arizona Cancer Center (Gerner), Chemistry (Wysocki), and the Valley Fever Center for Excellence, VA Hospital (Galgiani). The types of problems that will be solved for these investigators with the proposed LTQ-FT MS are grouped into (1) those involving detailed structural studies of specific proteins and protein complexes, (2) identification of post-translational modifications, and (3) structural characterization problems not involving proteins (drugs, prostaglandins) [unreadable] [unreadable] [unreadable] [unreadable]